Improvement of Piercing Process for Non-magnetic 50Mn18Cr4V Seamless Steel Tube

Aiming at the problems of the conventional manufacturing process of “ round billet + mechanically drilling” for the non-magnetic 50Mn18Cr4V high-manganese seamless steel tube i.e.,long processing cycle,high metal loss and high cost,a new process of “round billet + heating + piercing + cold-drawing forming” is developed. However,the said new process is prone to cause rolling jam and surface cracking defect of the shell during the hot-piercing step due to the temperature difference of the 50Mn18Cr4V round billet. The hot plasticity of this steel grade is studied via the thermal simulation test, and in turn, its optimal plastic deformation temperature is determined, based on which, the heating equipment and heating process are also optimized. The application of the optimized process has successfully eliminated piercing jamming and surface cracking defect of the shell,resulting in significant enhancement of the yield and reduction of the production cost.